This invention relates to newspaper presses for supplying continuous high speed newsprint web to the printing couples of newsprint presses. The printing press art, particularly that for color printing, is adversely affected by the present day tension system employing tension belts that "glaze" the newsprint as by planishing or calendering the newsprint underlying said belts, and thereby "streaking" the newsprint surface, it being a general object of this invention to eliminate streaking and leave the newsprint surface virtually untouched and therefore uniform in texture and surface quality.
Newsprint supplied in roll-form is 40 to 50 inches in diameter, and a full roll is 54 inches wide. In practice, the reel apparatus which supplies the newsprint web to the printing press is adjustable so as to accomodate fractional roll widths, i.e. 1/4 to full rolls. Therefore, prior art web tension systems are characterized by four identical tension belts, one for each quarter roll. And, each of these belts inevitably "streaks" the web surface to a noticable degree when applied to tension the web. Also, the presence of these belts reduces access to and the effective pasting area required for splicing new web to expiring web.
Prior art web tensioning control systems adversely calender the newsprint as it is supplied to the roll press. This calendering affects some of the fiber ends of the paper pulp which are sheared off and remain as loose particulate upon the newsprint surface, adhering thereto by static electricity. Therefore, when the newsprint reaches and contacts the impression (or blanket) cylinder for transfer of ink and moisture thereto, the "tack" of the ink causes said particulate to stick onto said blanket cylinder, thereby restricting the moisturized ink from the newsprint; and the moisture (water) grounds the static electricity. Consequently, the longer the roll press runs the greater is the particle paper fiber accumulation; and invariably to a degree readily detected by the naked eye. Because the paper dust particles are wiped onto the newsprint by the aforesaid tensioning belts, said particle accumulation is streaked longitudinally of the newsprint aligned with each of said tensioning belts. Heretofore, this dust particle accumulation has required STOPPING the press in order to wash away said accumulation of particulate, but this is only a temporary solution to the problem which reoccurs. It is an object therefore, to provide a system that virtually eliminates said streaking, eliminting STOPPING the press for blanket cylinder washdown and thereby preserving the surface texture and printing properties of the newsprint so that printing quality is maximized.
State of the art newsprint reels are comprised of three-armed spiders adjustably spaced on a central positioning shaft. There is a chucking spider that engages the core of the newsprint roll onto the spindle of a pastor spider that has a "contact point cover" which indicates the rotative position of the installed roll, whereby a splicing area or zone is established. Said rotative position is indicated by a timing pointer to coincide with a position sensing Hall Effect means that electronically senses said rotational position of the newsprint roll at any press speed or velocity, by which the paster brushes and knives are automatically timed to simultaneously splice a new web to an expiring web.
Tension of the newsprint web as it feeds into the printing press is regulated by a state of the art web force sensing roller, a "dancer roller", and by a lever system and air pressure regulator for web tensioning control. It is an object of this invention to apply this regulation to spindle braking applied directly to the core of the newsprint roll. In Accordance with this invention, a spindle braking means replaces each tension belt of the prior art systems.
A prerequisite for splicing a new web to a running web is the pre-drive or acceleration of a new roll to the same velocity as the running roll feeding the web into the press. This pre-drive system is state of the art, and is comprised of velocity sensors responsive to the speeds of the pre-drive belt and of the running web feeding the press. When the pre-drive peripheral speed of the new roll is up to the surface speed of the running web, the system is readied for the splice cycle.
It is an object of this invention to provide a newsprint web tension system with improved web-force control applied without adversely affecting other functions and physical properties of the newsprint. Accordingly, existent web force sensing, pre-drive system, and paster-knife system can remain state of the art, this invention being characterized by a multi-force braking mechanism applied to the core spindle of each of the three paster spider arms of the state of the art newsprint reels. In carrying out this invention, said braking mechanisms are comprised of stators attached to existent spider arms, and rotors attached to and driven by modified core supporting spindles, with brake actuating cyliners and controlled air pressure commutation thereto as required.
The prior art "Predrive" systems lack the sensitivity desired in order to avoid over reaction as well as under reaction, which heretofore has required activating a clutch/brake on the new roll accelerator mechanism that functions when the paster-knife mechanism is fired (actuated). This prior art clutch/brake is required because of the "transition period" during which the tension belts are inactive when transfering engagement from the expired newsprint roll to the new newsprint roll in the process of attachment.
The prior art requires a "transition period" control circuit that causes the "Predrive" to be alternately energized and de-energized, and/or re-energized etc., resulting in variable tension and particularly the misregistration of color printing. Consequently, it is not unusual for 350 to 700 full copies of a newspaper to be unacceptable; but these are not always discarded and the paying Advertisers complain about the significant number of poorly printed color adds that are arbitrarily delivered to the readers. Some newspapers throw away about 50 papers before and after a splice, but this is not commonplace. Previous presses ran slower and allowed the pressman to manually intercept the product stream and discard "waste"; but not so with state of the art printing establishments where the pressmen are housed in "quite rooms" and operate the presses remotely. All the good and bad is sold and the Advertisers continue to complain, it being an object of this invention to eliminate poorly printed advertising.
The typical prior art newsprint feed system operates as follows: After the paster-knife mechanism fires and while the Predrive belt is in contact with the new roll, but the new roll not yet in contact with the tension belts, the only means to stop the new roll in an emergency is with the clutch/brake and its control circuit. Accordingly, there is an electrical bypass set at a pre-set resistance in the brake control circuit so as to pass high braking current to the brake for this type of Emergency Stop (E-STOP). This control circuit is set to a fixed voltage value based upon the average mass which is equal to half of the newsprint mass running at a normal press velocity. However, this prior art control circuit does not compensate for smaller or larger width and/or diameter rolls, nor for changes in press velocity. Therefore, the same braking used for a 1/2 roll is arbitrarily used for a 1/4, 3/4 and full roll, for an E-STOP during the transition period, which results in abrupt changes in web tension and which often causes the web to break. Since it is common that a press starts with multiple rolls of the same nominal diameter, multiple splices can occur together. And, if any roll splice is "missed" an E-STOP results; several rolls can be in the transition period herein referred to. This occurs more often than one would expect, and usually results in a web break on any roll that is within said transition period; other than a 1/2 roll which is compatible with the average mass brake setting of the control circuit.
It is an object of this invention to instantaneously control core spindle "drag" whereby control is not delayed and web tension is not adversely affected. In other words, the conventional "transition period" is virtually eliminated, which is made possible by retraction of the new roll accelerator and instantaneously transfering control to Zero Stroke disc-brake calipers immediately responsive to air pressure variations dictated by the dancer roller. With the present invention, when the paster-knife fires there is little or no change in running web tension nor velocity change, while normal variations are instantaneously reflected as variable air pressures applied to the instantly responsive core spindle brake calipers controlling the new running roll.
It is an object of this invention to replace each prior art roll tensioning belt and long stroke air cylinders with a drag brake caliper applied directly to the running roll core spindle. It is also an object to apply drag braking to the expiring roll as well as the new running roll, whereby the expiring web and new running web have tension control thereof prior to and immediately after the pastor-knife mechanism fires. It is also an object to apply drag to the core spindle of the new newsprint roll, so that transition from the paste position into the running roll position is not adversely affected after firing the paster-knife mechanism. Consequently, there is no so-called "transition period"! With the system herein disclosed, the newsprint rolls do not run over speed nor under speed, and re-acceleration is never required, thereby eliminating alternate slack and excess tension variations and misregistration in roll press color printing.
An object of this invention is to apply core spindle drag commensurate with newsprint roll width. That is, each quarter width of a roll is subject to an initial drag value. Accordingly, each spindle brake disc is engaged by a multiplicity (four) of distinct brake calipers, one activated for each quarter of the newsprint roll carried by the spindle. A control feature is the variable drag brake caliper pressure responsive to running web tension sensed by the "dancer roller". And a fifth and sixth brake caliper provided for stopping the expired roll and for emergency STOP of the press functions.
It is an object of this invention to provide a newsprint roll supply for continuous press operation wherein the prior art tension belts and air cylinders are replaced by electrical drag brake selection whereby the press operator switches to the proper roll width, without the necessity of mechanically demobilizing one or more tension belts and associated air cylinders. As herein disclosed there are six disc-brake calipers at each newsprint core spindle, of which there are four one quarter width calipers, and a fifth and sixth caliper added for control and expired roll core braking when a splice is executed and all six calipers used. When the paster-knife mechanism fires, the core braking caliper or calipers continue to be applied to the expired roll to stop its rotation, as the pre-drive mechanism is deactivated, and the web tension instantaneously applied to the new running newsprint roll for consistant register in the press. Web tension control in instantaneously applied to the new roll by the air pressure dictated by the dancer roller and also sent to stop the expired roll so as to prevent paper spill. In order to stop the expired roll momentum quickly, the fifth and sixth brake calipers are activated, thereby eliminating the need for said prior art high cost--high maintenance electric core brake. When the new roll is indexed into running roll position the expired roll fifth and sixth air brake calipers are deactivated and the core spindle is ready for reloading a new roll. The paster-knife mechanism is retracted as the core brake calipers have continued tension control governed by the dancer roller without interruption (not by the clutch/brake of the prior art). In prior art systems when the new roll is in the Predrive mode or in the transition period, in an emergency the new roll must be stopped by applying the clutch/brake, which if in the prior art transition mode results in exaggerated tension, spilling of paper and web severing.
This new system is directly related to air pressure input to the core brake calipers responsive to the web tensioned dancer roller that determines the brake activating air pressures, resulting in constant torque control including emergency stops or any other mode. The prior art clutch/brake's emergency stop function is replaced by the aforesaid six brake calipers at each core spindle, there being no change in press operation to control and stop the press. The prior art clutch/brake's remaining function of maintaining press velocity of the new roll in the predrive mode is retained. The disc-brakes herein disclosed are air cooled with a stopping time from 2200 ft/min. with a 2000 pound newsprint roll of 6 seconds @ 70 psig. using five of the calipers.